An overview of glycogen

Glycogen (C24H42O21), also known as glycogen or glycogen, is an animal starch, branched chain polysaccharide from glucose, the glycoside chain for the α-type. Animal reserve polysaccharide. In mammals, glycogen is mainly found in the skeletal muscle (about 2/3 of the whole body glycogen) and liver (about 1/3), the other most organizations, such as the heart, kidney, brain, etc. Containing a small amount of glycogen. Lower animals and certain microorganisms (such as fungi, yeast), also contains glycogen or glycogen analogues.

The basic principles of glycogen

Glycogen from the D-glucose branches or straight-line composition, the most abundant in the liver and muscle. Periodic acid is a strong oxidant that oxidizes ethylene glycol (CHOH-CHOH) in glucose into two free aldehyde groups (-CHO). The free aldehyde group reacts with Schiff's reagent to produce a purple-red color, Content is proportional to. As the monosaccharides in the fixed, dehydrated and embedded in the process of histochemical operation was extracted, so the general tissue specimens can be displayed on the main polysaccharides, including glycogen, mucopolysaccharide, mucin, glycoprotein and sugar Fat and so on. Therefore, to determine whether this red material glycogen also need to conduct a control experiment. Glycogen can be saliva amylase hydrolysis, first with the role of saliva amylase and then PAS color, if the reaction is negative, then that is glycogen, and vice versa for the other polysaccharides.

Glycogen storage in the body

Glycogen storage in liver cells and muscle cell cytoplasm, the shape of the particles of varying sizes, in case of iodine is brown, soluble in water, the body necrosis, glycogen that is subject to damage, it is necessary to take fresh specimens and timely fixed. Glycogen is not equal to sugar, but a kind of carbohydrate. Carbohydrates from the perspective of histochemical techniques and biochemical classification is not consistent. From the perspective of histochemistry, sugars can be divided into polysaccharides, neutral sugar substances and acidic mucous substances and mucin and viscous lipid. Polysaccharide refers to glycogen, is composed of a number of glucose molecules to glycosidic bond composition of the polymer. When the body die, that is quickly broken down into glucose.

Animals and bacterial cells stored within the polysaccharide, composed entirely of glucose. In animals, the liver and skeletal muscle in the most abundant reserves, and starch in the role of plants. Glycogen in the body under the action of enzymatic synthesis and decomposition can maintain normal blood sugar levels, glycogen in bacteria for energy and carbon. Dry state of white amorphous powder, odorless, sweet. And iodine was brown red, showing maximum light absorption at 430-490nm. Partially soluble in water and colloidal solution, insoluble in ethanol. Structure and amylopectin is similar, mainly α-D-glucose, α (1 → 4) glycosidic bond condensation dehydration, and another part of the branch through the α (1→ 6) glycosidic bond. With the calculation of amylase hydrolysis after the formation of maltose and glucose. Can be used 30% sodium hydroxide treatment of animal liver, plus ethanol precipitation preparation.

Glycogen is composed of multiple glucose composed of branched macromolecular polysaccharides, molecular weight is generally 106-107 Dalton, up to 108 Dalton, is the body of sugar storage form, the molecular glucose mainly α-1, 4-glycosidic bond to form a straight chain, in which part of the α-1, 6-glycosidic links linked to form a chain, glycogen stored mainly in muscle and liver glycogen in muscle about 1-2% of total muscle weight of about For 400 grams of liver glycogen 6-8% of the total amount of about 100 grams. Muscle glycogen breakdown of energy supply to muscle contraction, glycogen breakdown of the main maintenance of blood glucose concentration.

Plants and animals (the digestive tract) amylase can act on glycogen, produce maltose and dextrin. In living cells, the degradation of glycogen from the non-reducing end of the beginning, one by one cut off the glucose, the formation of D-glucose-1-phosphate, and then through glycolysis and other sources of further decomposition of energy and synthesis of other biological molecules provide Need carbon frame. Due to the highly branched structure, about 8 to 10% of the glucose in the glycogen molecule is in the non-reducing end which can be utilized, which facilitates rapid and large-scale use in a short time when required and quick recovery of storage when not needed. For example, when muscle contraction is exercised, the required energy in the form of ATP is in the order of thousands to tens of thousands of times at rest, and these ATPs are largely dependent on the breakdown of glycogen to provide. Glucose, lactic acid, fatty acids, glycerol, certain amino acids can be through the appropriate metabolic pathways into glycogen storage; in vivo glucose synthesis process from glycogen called glycogen formation, from non-sugar substances generate glucose or glycogen The process is called gluconeogenesis.

The storage or consumption of glycogen in the human body is a process controlled by the hormone and the substrate. By regulating the enzymes involved in the synthesis and degradation process, the body's glycogen metabolism and blood glucose levels are properly controlled. Glycogen abnormal metabolism, the performance of glycogen storage disease, the reason is often due to the lack of the enzyme. For example, glucose-6-phosphate deficiency in patients with liver and kidney contains a large number of structural normal glycogen, clinical symptoms of hepatomegaly, extreme hypoglycemia, hyperlipidemia, hyperuricemia, ketosis and growth arrest.

Physicochemical Properties of Glycogen

The molecular structure of glycogen is similar to amylopectin. The sugar chains are mainly composed of D-glucose through α-1,4 linkages, and branched chains are formed by α-1,6 linkage. Glycogen molecules branch more than amylopectin, the average interval of 12 α-1,4-linked glucose is a branch point (amylopectin molecules in the average interval of about 20 to 25 glucose). Molecular weight range from several million to tens of millions. Glycogen is a white amorphous particles, reducing the very weak, soluble in water and produce milky colloidal solution, than the spin of about +200 °, the alkali tolerance is relatively strong, with the reaction of iodine reddish brown, in the alcohol In the solubility is small, add ethanol in aqueous solution can glycogen precipitation.

The role of glycogen

Glycogen is the body's most important energy supply material, mainly in the form of glucose is absorbed. Glucose is rapidly oxidized to supply energy. Carbohydrates constitute an important raw material of the body, involved in a variety of cell activities. Such as carbohydrates and protein synthesis of glycoproteins, antibodies, enzymes and hormones composition. Synthesis of glycolipids with lipids. Is the cell membrane and nerve tissue materials. Sugar has a special role in maintaining function. Carbohydrates have detoxification. Sufficient glycogen reserves, can enhance the resistance, the food supply enough sugar, can reduce the protein as the energy consumption.